Liquid level control having an annular permanent magnet for actuating a mercury switch



Dec. 29, 1964 YD 3,163,731

LIQUID LEVEL CONTROL HAVING AN ANNULAR PERMANENT MAGNET FOR ACTUATING A MERCURY SWITCH Filed July 25, 1961 FIG.1

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I 53 48 F1615 l "i 19 I 412 I 27 ON 2s 29 I l g INVENTOR. I I FRANKJ LYDEN P ATTORNEY United States Patent Oflflce 3,163,731 Patented Dec. 29, 1964 3,163,731 LIQUID LEVEL CONTROL HAVING AN ANNULAR PERMANENT MAGNET FOR ACTUATING A MERCURY SWITCH Frank J. Lyden, 1115 N. 9th St., Manitowoc, Wis. Filed July 25, 1961, Ser. No. 126,570 Claims. (Cl. 20084) This invention relates to liquid level controls of the general type including an electric switch responsive to liquid level. Although not limited thereto, the invention is particularly uesful in detecting the oil level in bearing reservoirs, such as of automated power plants.

An object of the invention is to provide an improved and reliably operating liquid level control including a float switch which is magnetically actuated in response to changes in liquid level, the device being so arranged as to protect the switch and wiring connections and to afford a relatively compact, rugged and easily assembled construction.

Another object is to provide a liquid level control in which the magnetically actuated switch is of the sealed mercury tube type and is surrounded by a float-carried actuating magnet.

A further object is to provide a liquid level control having the switch and surrounding float disposed in a float housing which also: permits visual inspection of the oil level.

A still further object is to perfect details of construction generally.

The invention further consists in the several features hereinafter described and claimed.

In the accompanying drawing,

FIG. 1 is a vertical sectional view of a liquid level control constructed in accordance with the invention and connected to a liquid reservoir or tank;

FIG. 2 is a top plan view of the device;

FIG. 3 is a side elevational view of the device but showing a different form of connection to the liquid reservoir;

FIG. 4 is a diagram showing the range of On and Off conditions of a float-actuated switch of the device;

FIG. 5 is a diagram similar to FIG, 4 but showing a further On condition of the switch when the float is in its lowermost range of travel;

FIG. 6 is a sectional detail view taken generally on the line 6-6 of FIG. 1;

FIG. 7 is a vertical detail view of a tubular switch housing, and

FIG. 8 is a vertical detail view of a magnetically actuated mercury tube switch and associated mounting parts.

In the drawing, the numeral 10 designates a float housing which comprises spaced upper and lower heads 11 and 12 and an intervening upright cylindrical shell 13 of transparent glass or transparent plastic, such as Lucite, the opposite ends of the shell fitting in circular recesses 14 formed in the respective heads and bearing against annular gaskets 15 in the heads. The housing heads 11 and 12 are formed of non-magnetic material, such as an aluminum alloy, and comprise respective hexagonal body portions 16 and 17 having respective marginal flanges 18 and 19 of generally triangular shape, as seen in FIG. 2. The marginal flanges of the vertically spaced heads are connected by vertical corner studs 20 of non-magnetic metal, such as brass, which clamp the transparent shell between the heads, the studs being surrounded by tubular spacers 21 of non-magnetic metal, such as brass.

The housing heads are further connected by a coaxially extending tubular switch housing 22, hereinafter more fully described, the switch housing being formed of nonmagnetic material, such as brass. A magnetically actuated mercury tube switch 23, hereinafter more fully described, is axially mounted in the tubular switch housing. The float housing forms therein a float chamber 24 of annular cross-section, the side Walls of the float chamber being defined by the inner wall of the cylindrical shell 13 and the outer cylindrical wall of the vertically extending tubular switch housing 22. An annular magnetic-carrying float 25 of cylindrical shape loosely surrounds the tubular switch housing and is vertically movable in the float chamber to actuate the switch. The float is hereinafter more fully described.

A vertical stud 26 has its upper end threaded centrally into the lower end of the lower float housing head and is clamped thereto by a lock nut 27. An angle bracket 28 has its upper horizontal flange apertured to receive the stud which is clamped thereto in vertically adjusted position by a pair of nuts 29. The vertical flange of the bracket is apertured to receive clamping screws 30 for mounting the bracket on a switch support 31, such as a part of an oil tank or reservoir 32, thus rigidly supporting the float housing. In one application of the invention the reservoir forms part of a bearing assembly of an automated power plant.

The lower housing head 12 has formed therein an angular passage 33, the inner vertical end of which communicates with the lower end of the float chamber, and the outer horizontal end of which opens at a side face of the hexagonal head portion 17 and is screw-threaded to receive an end of a horizontal pipe 34, the other end of pipe being connected to the oil reservoir 32. The oil level in the float chamber is thus the same as the oil level in the reservoir.

The upper housing head 11 has formed therein an angular passage 36 similar to the passage 33 in the lower head. In a preferred form of the invention, shown in FIG. 1, an elbow 37 is screwed into the outer end of the upper head passage 36, and an air vent plug 38 is screwed into the downturned outer end of the elbow, the plug also forming an air filter.

In another form of venting arrangement, shown in FIG. 3, the upper housing head 11 and the oil reservoir 32 are connected by a horizontal vent pipe 37. This arrangement is provided when the reservoir is under pressure or vacuum.

The centrally apertured float 25 is guided in its vertical travel by the tubular switch housing 22 and is tree to turn to random positions about its vertical axis. The float is made of suitable material, such as foamed polystyrene, and has coaxially secured therein, as by a press fit, an annular permanent magnet 39, such as of Alnico V, the magnet being in the form of a short tube, and the inner cylindrical surface of the magnet lying close to the outer cylindrical wall of the tubular switch housing. The tubular magnet is suitably polarized, as by having a north pole at one end and a south pole at the other end.

About midway of its height the transparent float housing shell 13 is provided with a surrounding opaque line or ring 40, black or colored, inlaid in the shell and forming an index mark. When the float is in its normal position the top of the float registers with this mark. As an alternative, the index mark may directly indicate the normal level of the liquid in the float chamber.

The tubular switch housing 22 has an enlarged cylindrical upper end portion 41 which fits in a vertical bore 42 formed axially in the upper float housing head 11 and which has a hexagonal top flange 43 bearing on a washer 44 of soft metal, such as lead, resting on the top face of the upper head. The switch housing has a reduced closed lower end 45 which is screw-threaded into a bore 46 formed axially in the lower head. An annular stop collar 47 surrounds the tubular switch housing and rests on the upper face of the lower head to limit the downward travel of the float, the collar having an inturned bottom flange 48 confined between the lower head and a down wardly facing annular shoulder 49 formed on the switch housing. The tubular switch housing has formed therein a stepped bore comprising a lower section 50, a slightly enlarged intermediate section 51, and a still larger screwthreaded upper section 52, the junction between the lower and intermediate bore sections forming an upwardly facing annular shoulder 53.

The magnetically actuated mercury tube switch 23, which is of conventional type per se, extends vertically in the lower portion of the switch housing in inverted position and includes a sealed tubular glass envelope 54 fixed at its upper end to a slightly larger cylindrical base 55 of insulating material, the switch being provided with a pair of flexible insulated leads 56, which extend upwardly from the base through the switch housing bore and are equipped with terminals 57. The tubular glass envelope of the switch extends with a slight clearance in the lower bore section 50 of the switch housing, and the lower annular edge of the base adjacent to the glass envelope bears on one or more height-adjusting washers 58 which rest on the annular shoulder 53 in the switch housing. The switch is clamped firmly in position by a spacer sleeve 59 which slidably fits in the housing bore section 51 above the switch base and is pressed downwardly by a slotted ring nut 60 threaded in the upper bore section 52, the lower end of the sleeve engaging an annular gasket 61 which bears on the upper end of the switch base 55. The switch 23 includes therein a pair of contact wires 62 and 63 which project downwardly from the upper end of the switch envelope, the lower end of the wire 62 extending into a mercury globule 64 contained in the lower end of the envelope, and the wire 63 being resiliently mounted to permit lateral deflection thereof and having its lower end movable into and out of the mercury to make and break contact. The laterally defiectable wire 63 carries a magnetizable plate or armature 65 which cooperates with the annular float magnet 39 to actuate the switch. In a preferred arrangement, the mercury switch 23 is of the normally closed type, as shown, but for some applications the switch can be of the normally open type. In the normally closed switch the laterally displaceable armature-carrying contact wire 63 is spring-biased inwardly into engagement with the mercury globule, and is magnetically displaceable out of engagement with the mercury to open the switch.

In the arrangement shown in FIG. 1, the float magnet will actuate the normally closed switch to open or Off position when the float is in its lower range of travel, this range extending from an upper position slightly lower than the position shown in FIG. 1 to a lower position in which the float engages the stop collar 47. When the float rises from its lower range of travel, as to the position shown in FIG. 1, the magnetizable switch armature 65 is no longer in the field of influence of the float magnet, and the switch thereupon closes and remains closed during any further upward travel of the float. The On and Off switch conditions for various vertical positions of the float are shown diagrammatically in FIG. 4.

In some instances, it is desirable that the switch have two closed or On positions and an intermediate open or Ofl position as the float moves through its range of vertical travel. This is accomplished by removing the stop collar 47, whereupon the switch will be in closed or On position when the float is in the lowermost part of its extended range of travel. This is shown diagrammatically in FIG. 5.

When the mercury switch is of the normally open type, the switch conditions shown in each of FIGS. 4 and will be reversed.

The switch leads 56 extend upwardly from the tubular switch housing into a cup-shaped conduit housing 66 which is clamped to the upper end of the tubular switch housing 22 by a peripherally shouldered bushing or adapter 67 having its tubular lower end threaded into the upper end of the switch housing. An enlarged shoulderforming intermediate portion 68 of the bushing bears on a washer 69 resting on the bottom wall of the cup-shaped conduit housing, and sealing gaskets 70 and an intermediate metal washer 71 are interposed between the conduit housing 66 and the upper end of the switch housing. The bushing 67 has an intermediate cross bore 72 to pass the switch leads, and the upper end of the conduit housing 66 is closed by a centrally apertured, marginally flanged cap 73 which is secured to the housing by a central screw 74 passing through the cap and having its lower end threaded into the upper end of the bushing. The head of the screw bears on a washer 75 which in turn bears on a sealing gasket 76 seated in the cap. The conduit housing 66 has an internally threaded tubular side wall boss 77 for connection to a conduit pipe 78 adapted to receive circuit conductors, not shown, for connection to the terminals of the switch leads. The switch is connected in any suitable control or indicating circuit, not shown. The conduit housing 66 may be shifted to various angular positions about its vertical axis to suit the conduit pipe installation.

When the control device is in use, oil is deposited in the oil tank or reservoir 32, as by pump means, not shown, until a normal oil level is reached. During this operation, oil will rise in the float chamber 24 to the same level, buoying up the magnet-carrying float 25 and thus permitting the closing of the previously open mercury switch 23 to establish a suitable control circuit, not shown. By way of example, the control circuit may be arranged to prevent starting of the machine unless the oil is at its normal level. If the oil level subsequently drops below a predetermined point, the downward displacement of the magnet-carrying float will bring the magnet into attracting relation to the switch armature, thus actuating the mercury switch to open position. The opening of the switch may be used to eflect one or more control functions, such as producing a warning signal, initiating an oil pumping operation, or shutting down the machine.

I claim:

1. In a liquid level control, a float housing including a vertical transparent tubular shell and upper and lower heads between which said shell is secured, a tubular switch housing extending vertically within said shell and rigidly connecting the upper and lower heads, said float housing having therein a liquid-receiving float chamber of annular cross-section, said shell and switch housing defining the side walls of said float chamber, said lower head having a liquid passage communicating with said chamber, a magnetically actuated mercury tube switch mounted in stationary position in said tubular switch housing, said switch housing having non-magnetic side walls, an annular float vertically movable in said chamber and surrounding said tubular switch housing, and an annular magnet carried by said annular float at the inner portion thereof and surrounding said switch housing in adjacent relation thereto for actuating said switch upon a change of liquid level in said chamber.

2. In a liquid level control, a float housing having a float chamber therein and having a top wall with an opening, mounting means supporting said float housing at the lower end of said housing, a liquid-tight tubular switch housing secured in said top wall opening and extending vertically in said float chamber, said tubular switch housing having non-magnetic side walls, a magnetically actuated mercury tube switch mounted in stationary position in said switch housing, a float vertically movable in said chamber and surrounding said tubular switch housing, an annular magnet carried by said float and surrounding said switch housing in adjacent relation thereto for actuating said switch upon a change of liquid level in said chamber, a conduit housing disposed at the upper end of said switch housing, a clamping bushing rigidly securing said conduit housing to said tubular switch housing and having a screw-threaded engagement with the upper end portion of said switch housing, and conductor leads connected to said switch and extending upwardly therefrom through said tubular switch housing and bushing and into said conduit housing.

3. In a liquid level control, a float housing having a float chamber therein and having a top wall with an opening, a liquid-tight tubular switch housing secured in said top wall opening and extending vertically in said float chamber, said tubular switch housing having non-magnetic side walls, a magnetically actuated mercury tube switch mounted in stationary position in said switch housing, a float vertically movable in said chamber and surrounding said tubular switch housing, an annular magnet carried by said float and surrounding said switch housing in adjacent relation thereto for actuating said switch upon a change of liquid level in said chamber, a conduit housing disposed at the upper end of said switch housing, a clamping bushing rigidly securing said conduit housing to said switch housing and having a coaxial screwthreaded engagement with the upper end portion of said switch housing, and conductor leads connected to said switch and extending upwardly therefrom through said tubular switch housing and bushing into said conduit housing, said conduit housing having a side opening and being angularly shittable about the vertical axis of said tubular switch housing to change the orientation of said side opening.

4. in a liquid level control, a float housing including top and bottom walls and a side wall, said top wall having an opening therein, a liquid-tight tubular switch housing extending vertically in said float housing between said top and bottom walls and having an axial bore and nonmagnetic side walls, said tubular switch housing having an upper portion extending through said top wall opening, the lower end of said tubular switch housing being closed and having a screw-threaded connection with said bottom wall, said float housing having therein a liquidreceiving float chamber surrounding said tubular switch casing, a magnetically actuated mercury tube switch of tubular shape extending vertically in the bore of said switch housing and including a top base, clamping means in said switch housing bore engaging the upper end of said switch base and having a screw-threaded connection with the switch housing bore, a float vertically movable in said float chamber and surrounding said tubular switch housing, and an annular magnet carried by said float and surrounding said switch housing in adjacent relation thereto for actuating said switch upon a change of liquid level in said chamber.

5. In a liquid level control, a float housing having a liquid-receiving float chamber therein, a tubular switch housing extending vertically in said float chamber and having non-magnetic side walls, said tubular switch housing having therein a coaxial bore closed at its lower end and further having an inwardly projecting upwardly facing annular shoulder at an intermediate point of the length of said bore, a magnetically actuated mercury tube switch disposed vertically in said bore and including a tubular envelope and a superposed cylindrical base of larger diameter, said switch base being peripherally supported by said annular shoulder, clamping means in said switch housing bore engaging the upper end of said switch base and having a screw-threaded engagement with said bore, a float vertically movable in said float chamber and surrounding said tubular switch housing, and an annular magnet carried by said float and surrounding said tubular switch housing in adjacent relation thereto for actuating said switch upon a change of liquid level in said float chamber.

Reierences Cited in the file or this patent UNITED STATES PATENTS 2,590,680 Campbell Mar. 25, 1952 2,820,865 McKinnies Jan. 21, 1958 2,927,176 Auld et al. Mar. 1, 1960 FOREIGN PATENTS 669,932 Great Britain Apr. 9, 1952 

1. IN A LIQUID LEVEL CONTROL, A FLOAT HOUSING INCLUDING A VERTICALL TRANSPARENT TUBULAR SHELL AND UPPER AND LOWER HEADS BETWEEN WHICH SAID SHELL IS SECURES, A TUBULAR SWITCH HOUSING EXTENDING VERTICALLY WITHIN SAID SHELL AND RIGIDLY CONNECTING THE UPPER AND LOWER HEADS, SAID FLOAT HOUSING HAVING THEREIN A LIQUID-RECEIVING FLOAT CHAMBER OF ANNULAR CROSS-SECTION, SAID SHELL AND SWITCH HOUSING DEFINING THE SIDE WALLS OF SAID FLOAT CHAMBER, SAID LOWER HEAD HAVING A LIQUID PASSAGE COMMUNCATING WITH SAID CHAMBER, A MAGNETICALLY ACTUATED MERCURY TUBE SWITCH MOUNTED IN STATIONARY POSITION IN SAID TABULAR SWITCH HOUSING, SAID SWITCH HOUSING HAVING NON-MAGNETIC SIDE WALLS, ON ANNULAR FLOAT VERTICALLY MOVABLE IN SAID CHAMBER AND SURROUNDING SAID TUBULAR SWITCH HOUSING, AND AN ANNULAR MAGNET CARRIED BY SAID ANNULAR FLOAT AT THE INNER PORTION THEREOF AND SURROUNDING SAID SWITCH HOUSING IN ADJACENT RELATION THERETO FOR ACTUATING SAID SWITCH UPON A CHANGE OF LIQUID LEVEL IN SAID CHAMBER. 